What is the molarity of a solution consisting of 0.750 mol NaCI dissolved in 4.50 L of solution
I got 14.61mol is that right?

No, that's not correct. You should realize that it is wrong because the answer should be M (molarity: moles per liter) and you say you got
14.61 mol. Wrong units, wrong answer. The units of the answer - moles per liter - tell you exactly how to solve the problem. Do you realize that "per" means "divided by"? Try it again and show your work and your answer.

0.750 mol NaCl dissolve in 4.50 L so molarity will be
0.75/4.50 = 0.16 M ( mol/L)